The advanced touch panel technology has resulted in many consumer electronic products, such as personal digital assistant (PDA), global positioning systems (GPS), and the like being equipped with touch panels
Before iPhone™ was released, resistive touch panels were generally used on small sized portable electronic devices because these panels were low-cost, reliable, and had sufficiently matured. In addition, resistive touch panels cannot track more than one finger touch, restricting resole multipoint touches Once the iPhone™ was announced, there existed a need of projected capacitive touch panels became desirable as these panels enable multipoint touch.
As shown in FIG. 12, a conventional protected capacitive touch panel comprises a glass base (91), a touch sensing circuit layer (92), a conductive wire layer (93), an insulator layer (94), a conductive glue layer (95), a flexible printed circuit (FPC) board (96), an optical glue layer (97), and a glass cover (98), The glass base (91) includes a circuit surface (911). The touch sensing circuit layer (92) includes touch sensing circuits. Further, the touch sensing circuit layer (92) and the conductive wire layer (93) are electronically connected together and formed on the circuit surface (911) of the glass base (91). The insulator layer (94) is formed such that it covers the conductive wire layer (93). The insulator layer (94) includes a breach that partially exposes the conductive wire layer (93). Additionally, the conductive glue layer (95) is formed on the breach to cover the exposed conductive wire layer (93). The FPC board (96) is attached to the conductive glue layer (95), thereby electronically connecting to the conductive wire layer (93) via the conductive glue layer (951 The optical glue layer (97) is formed on the touch sensing circuit layer (92) and the insulator layer (94). Moreover the glass cover (98) includes an operating surface (981) and an adhering surface (982). The adhering surface (982) is adhered to the optical glue layer (97). The operating surface (981) of the glass cover (98) may function either as a touch surface or a protection cover to protect the touch sensing circuit layer (92), the conductive wire layer (93) and the conductive glue layer (95) on the glass base (91).
The conventional projected capacitive touch panel requires two glasses (91, 98) which are fixed by the optical glue layer (97), as a result, the touch panel exhibits the following aspects
1. The optical glue layer (97) is positioned between the glass base (91) and the glass cover (98), reducing penetrability of the conventional projected capacitive touch panel.
2. Adhering the two glasses (91, 98) requires great accuracy so affecting manufacturing yield rate. Current techniques cannot provide high accuracy of adhering the glasses for increasing yield rate of manufacturing the conventional projected capacitive touch panel.
3. Transparent optical glue layer (97) allows the insulator her (94) and the FPC board (96) to be visible from the operating surface (981) of the glass cover (98). The conventional projected capacitive touch panel installation on an electronic device requires a casing on the electronic device having opaque rims to cover the insulator layer (94) and the FPC board (96). However, such design limitation restricts application and also requires accurate machining, increasing cost and reducing manufacturing yield.